Mikulas Patocka 17cedf3ba1 dm bufio: make the parameter "retain_bytes" unsigned long ...

commit 13840d3801 upstream.

Change the type of the parameter "retain_bytes" from unsigned to
unsigned long, so that on 64-bit machines the user can set more than
4GiB of data to be retained.

Also, change the type of the variable "count" in the function
"__evict_old_buffers" to unsigned long.  The assignment
"count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];"
could result in unsigned long to unsigned overflow and that could result
in buffers not being freed when they should.

While at it, avoid division in get_retain_buffers().  Division is slow,
we can change it to shift because we have precalculated the log2 of
block size.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2017-05-25 15:46:12 +02:00

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